1. Technical Field
The present invention relates to ratchet wrenches, and more particularly to a ratchet wrench having a change-gear set and a positioning rod that, when cooperating, drive a tool part in an increased speed.
2. Description of Related Art
For screwing a threaded part (e.g. a threaded bolt or a nut) to tight or loose, it is common to use an open-end wrench or a box wrench. However, for operation performed in spatially limited environments, using such a basic wrench can consume considerable time as the user has to repeatedly engage the wrench with the workpiece, rotate the wrench and remove the wrench from the workpiece. For improving the basic wrenches, ratchet wrenches have been developed to eliminate the need of repeated engagement and disengagement between the wrench and the workpiece. More particularly, a ratchet wrench uses a unidirectionally drivable ratchet so that it drives the workpiece when operated in one direction and runs idly without driving the workpiece when operated in the other direction, thereby simplifying and speeding up the overall operation.
Nevertheless, it is clear that in the operation of a conventional ratchet wrench the idle running in the non-driving direction is still a waste, so there is a room for improving the operational efficiency of the conventional ratchet wrenches.
In addition, Taiwan Patent No. M427237, titled “ROTATIONAL MECHANISM FOR HAND TOOL”, discloses another wrench that has a turntable, a driving head and an accelerating wheel set positioned therebetween, so that when the turntable drives the driving head through the accelerating wheel set, the wrench can drive a workpiece in an increased speed. However, operation of such an existing wrench requiring a user to use his/her one hand to hold the turntable and use his/her the other hand to operate the same components is inconvenient and difficult to perform in confined operational space (e.g. in a vehicle's engine room).